A criminal swindle of the nation's $64.7billion food- stamp program is playing out at small neighborhood stores around the country, where thousands of retailers are suspected of trading deals with customers, exchanging lesser amounts of cash for their stamps.

Investigators have opened a criminal probe exploring whether poisoning or some other scenario played a role when 21 prize polo horses began collapsing Sunday during preparations for a match in Florida and later died, officials say.

A Virginia plant owned by the same company linked to the salmonella outbreak in peanut products was cited last year for inadequate conditions, including mouse droppings in a warehouse, a live bird inside the plant and mold on totes holding peanuts, according to Virginia state inspection records.